This book investigates the argument from queerness against moral realism, famously put forward by J. L. Mackie in Ethics: Inventing Right and Wrong (1977).

The book can be divided into two parts. The first part, roughly comprising chapters 1 and 2, gives a critical overview of Mackie’s metaethics. In chapter 1 it is suggested that the argument from queerness is the only argument that poses a serious threat to moral realism. A partial defense of this idea is offered in chapter 2 via a discussion of Mackie’s argument from relativity, which is concluded to fail for reasons that generalize to other influential arguments against moral realism. Chapter 2 also explores Mackie’s moral semantics at length. The key notion of authoritative prescriptivity is analyzed, and a new interpretation of Mackie’s error theory is defended. In the second part, consisting roughly of chapters 3 and 4, the argument from queerness is taken apart and put back together, resulting in several different versions. Chapter 3 discusses three different supervenience-related arguments, all of which are found to be unpersuasive. Chapter 4 develops two different versions of the core argument from queerness, focusing on authoritative prescriptivity. A total of thirteen objections are discussed and rejected. It is concluded that the two arguments do indeed refute the targeted versions of moral realism. Finally, in chapter 5 the entire discussion is briefly summarized.